The SNP celebrates its 75th anniversary this year in good heart and mind. The party now finds itself two and a half successful years into office, having won the 2007 Scottish Parliament elections. It has been setting the political landscape of Scotland since, wrong-footing opponents and preparing to make progress towards holding an independence referendum.

The forthcoming week sees the publication of the first ever study of the contemporary SNP, ‘The Modern SNP: From Protest to Power’, addressing who the Nationalists are, where the party’s support comes from, looking at its ideals and policies and examining its thinking on independence.

Who are the SNP then, and what impact have they had on Scottish politics? Firstly, any study of the Nationalists has to acknowledge that the party and its members have been a breath of fresh air in the stultified atmosphere of Labour councillors versus Tory grandees which characterised much of 1950s politics. Scottish politics were phenomenally dull in terms of personnel before the Nats, with the odd exception. They were suffocatingly male, and then along came Winnie, Margo and a whole host of other SNP politicians who didn’t come from the Labour or Tory ‘clublands’.

Secondly, SNP politics and politicians caught and shaped the emerging Scottish dimension from the mid-1960s onward and contributed hugely, along with others, to the pressure which led to the establishment of the Scottish Parliament. In the 1970s it was the electoral threat of the SNP which brought Labour back to devolution. Scottish politics would be a lot more boring, and less distinct without the modern SNP.

The SNP, its members and supporters are addressed in contributions from James Mitchell, Robert Johns and Lynn Bennie drawing on their national survey of SNP members, and John Curtice on the party’s vote.

Mitchell et al finds that SNP members are older than is assumed, more male and largely middle class – drawing from the same pools as the other parties. SNP members are not surprisingly overwhelmingly supporters of independence – with everything else secondary. However, there is strong support for the idea that the primary goal of independence may need to take second place to compromise and co-operation to progressing to this goal.

SNP support in 2007 varied relatively little across Scotland – from owner occupiers to council tenants, Catholics to Protestants – with only one group having a majority of SNP support, namely private rented tenants.

This takes us to the issue of what the party believes and what motivates party members in their hearts. In the party’s soul, can be found a vision and utopia of Scottish statehood and independence, which carries precedence over any division of left and right.

Thus, conventional wisdom in the last decade has emphasised the social democratic credentials of the party. This states, rather in the way ‘New Labour’ created a caricature of ‘Old Labour’ to emphasise its break with the past, that there was an ‘old SNP’ which was a ‘catch-all party’ which did not see itself in conventional ideological terms. This party has now become transformed into a ‘new SNP’ which has positioned itself firmly on the centre-left, attempting to win former Labour voters and outflank the party on the left.

While not disputing the centre-left nature of today’s Nationalists, what drives the party in its soul is not social democracy, but a sense of being ‘Scotland’s party’. This can at times be articulated as an ‘I believe in Scotland’ outlook, which has seen some of the party’s opponents believe they are perceived by the Nationalists as being ‘anti-Scottish’. This infuriates Labour, Conservative and Lib Dem politicians who believe that the SNP see themselves as having exclusive ownership of ‘Scotland’.

The SNP have with their emergence, rise and securing of office, changed Scottish politics, and threatened and put out their political opponents – both north and south of the border.

No battle has been more bitter than the Labour-SNP struggle, examined in-depth by myself in the book. What this study shows – from the origins of the expletive ‘tartan Tory’ in the mid-1960s to lambast the Nationalists – is that Labour’s detestation of the Nationalists has worked much more to Labour’s disadvantage and the Nationalists benefit.

SNP spokespeople have at points used indiscrete and offensive language about Labour politicians – think of Alex Neil comparing George Robertson to ‘Lord Haw Haw’. However, what has been more common has been Labour spokespeople through the years – from Willie Ross to George Robertson to Iain Gray today – pathologising the SNP and refusing to normalise relations with them.

Robert McNamara, JFK’s Secretary of State, in the film ‘The Fog of War’, observed that the first rule of conflict is to ‘empathise with your enemy’ and refuse to dehumanise them so you can understand them better. This is something Labour has consistently refused to do, and seem in opposition in Holyrood to have no want to change.

In parts of Scotland and Britain there are still people with an instinctual gut distrust and dislike of the Nationalists. Often these are older voters who have an attachment to the idea of ‘Britain’. In England, parts of centre-left opinion in the media and intelligentsia cannot understand that the SNP are a conventional centre-left party in Scotland and not outsiders or some anti-system force.

A recent article by academic Tom Gallagher on the website ‘Harry’s Place’ compared Alex Salmond to Hitler and Mussolini. Others lump the rise of the SNP with the BNP and see all nationalisms as bad and xenophobic. Such distortions of the SNP’s character only serve to emphasis that many in England just don’t understand Scottish politics and certainly don’t understand the SNP.

As for the record of the SNP Government two visible trends are evident. First, on policy the record is patchy. Across economic, social and cultural policy – analysed by Jim and Margaret Cuthbert, Stephen Maxwell and Philip Schlesinger respectively – the party has drawn ideas from the grain of prevailing orthodoxies rather than challenge them. This has meant it has taken many of its policies from the same narrow well as New Labour and the Cameron Conservatives, which may store up problems, post-crash, for the future.

Second, the role of Scotland’s Government – now recognised as such across the world – has dramatically changed, underlined by the al-Megrahi case. Alex Salmond has first transformed the SNP into an election-winning party, and then transformed the perception of Scotland’s Government.

The cause of Scottish independence matters not just as a Scottish, but UK and international story. Why do five million Scots matter across the globe? The answer is to be found in the nature of the UK, the geo-political space it occupies, and the fixation of the British political classes with a one-sided ‘special relationship’. And then there is the thorny issue of the British nuclear deterrent being based in Scotland at Faslane.

Whatever Michael Portillo and some Tory parliamentary candidates state, Scottish independence is a direct threat to the modus operandi of the United Kingdom, and something its governing classes would do everything to avert.

Independence matters and it is the last major faultline in Scottish politics. A referendum is inevitable – if not in 2010 – then the near future. We know that at points Gordon Brown and David Cameron have seriously given consideration to holding a vote.

What is a given is that constitutional change is coming whoever wins the 2010 UK election. If we consider the demise of old style unionism – we can see that the old union is unsustainable and change is coming. However, it is also true that conventional nationalism is also in decline – so that any change may stop short of traditional notions of independence and involve new kinds of arrangements between the nations of the UK.

This will involve a contest between the parties to see who can accommodate their vision best to the politics of globalisation and interdependence. Westminster parties like to pretend this makes the SNP’s ‘narrow separatism’, as Gordon Brown labelled the party this week, obsolete, but the British political classes have had huge problems with these issues, particularly vis-a-via sharing powers with the EU.

What does the future hold for the SNP and its contribution to Scottish politics? We can say with some certainty a few things about the direction of travel in the future which will entail the continuation of the Scottishing of Scottish politics. This will see the Scottish Government’s influence and profile continue to rise north of the border, our Westminster voice and influence continue to decline, and the politics of an independence referendum cause difficulties for every party and necessitate further thinking by the Nationalists.

This is an agenda which mostly suits the SNP and plays to its strengths. At the same time the party faces a range of formidable tasks. These include how to challenge and break from the embrace of ‘the Scottish consensus’ of managed decline and develop policy post-crash which departs from the orthodoxies of recent decades and informs a different vision of independence. While undertaking these, the party has also to aid the emergence of the next generation of SNP leaders and politicians post-Salmond to maintain the party’s distinctiveness and sharpen its radical edge.

This is a stiff set of challenges for any party, but in its 75th year, the SNP can look with some confidence to the future.

Gerry Hassan (ed.), The Modern SNP: From Protest to Power, Edinburgh University Press £19.99.